Distribution Network Operators (DNOs) are licensed companies that own and operate the network of towers, transformers, cables and meters that carry electricity from the national transmission system and distribute it throughout Britain.
DNOs distribute electricity from the transmission grid for a large geographical area, whereas IDNOs distribute electricity from either DNOs, or the transmission network, to smaller local areas. Both DNOs and IDNOs are responsible for connection line faults and maintenance.
DNOs manage distribution networks from 240V to 400 kV through underground and overhead power lines, this covers commercial, industrial and residential properties. They’re also responsible for allocating Meter Point Registration Numbers (MPRNs), the unique identifiers for individual supply points that correspond to respective regions. Their systems connect directly to the central database of electricity supply points.
As DNOs are natural monopolies, they must be regulated by Ofgem to protect consumers from overcharging. Ofgem also stipulates that DNOs must connect customers when requested, while IDNOs do not. Costs are based on connecting the customer to an electrical supply, reinforcing networks, and rebates to the previous connection operator.
There are 14 licensed DNOs owned by six different groups that cover specific geographically defined regions of Britain.
3. Scottish and Southern Energy
4. ScottishPower Energy Networks
5. UK Power Networks
6. Western Power Distribution
Independent Distribution Network Operators are companies that develop, own, operate and maintain smaller, local electricity distribution systems within the DNO network.
IDNOs are connected to Distribution Network Operators (DNOs), either directly, or through other IDNOs. They carry power to homes and businesses around Britain. Unlike DNOs, they're not bound to any specific geographical region and can therefore offer their services to a wider range of customers.
An Independent Connections Provider (ICP) is an accredited company that carries out works on behalf of clients on the electricity network. These companies are owned by both DNOs and IDNOs.